The effect of processing or concentration of dried distillers grain with solubles on the growth of finishing lambs.

Dried distiller grains with solubles (DDGS) are a popular byproduct used in the livestock feed industry as it is a cost-effective feedstuff that is rich in crude protein and minerals. However, a common concern related to the use of DDGS in livestock diets is the negative impact that affects animal dry matter intake (DMI) and growth. To further investigate this challenge, the experiments aimed to evaluate the effect of feeding 1) two different diets, control versus heat processed DDGS or 2) increasing the concentration of DDGS and its effect on body weight (BW), average daily gain (ADG), DMI, and gain to feed ratio (G:F) in finishing lambs. In experiment 1, both diets were the same except for the heat processing of DDGS; the control diet used a commercial DDGS source directly from the supplier and the processed diet contained the same commercial DDGS source that differed through additional heat processing. For DDGS heat processing, 40% moisture was added to the DDGS and heated at 150 °C for 70 min. After the heating process, the DDGS was placed in a second oven at 56 °C for 2 d to allow for humidity evaporation. Lambs (n = 34), blocked by sex and BW, were housed in pens (2 to 3 lambs/pen, 6 pens/treatment) and were fed for 42 d. Lamb DMI was measured daily, and BW was measured every 14 d. In experiment 2, lambs (n = 75) were blocked by BW (5 lambs/ pen, 5 pens/treatment) and fed diets differing in inclusion rates of DDGS (10%, 20%, and 30%). The feeding period lasted for 56 d, and lamb DMI and BW were measured daily or every 28 d, respectively. In both experiments, diets were isonitrogenous, and the feeding procedure utilized slick bunk management. Data were analyzed in SAS using a mixed model considering the treatments as fixed effects and pen and block as random effects. In experiment 1, there were no treatment differences (P ≥ 0.13) in ADG, DMI, and G:F in finishing lambs. In experiment 2, a linear and quadratic contrast were used to separate the mean and demonstrated that increasing the concentration of DDGS decreased lamb DMI (linear P < 0.01; quadratic P = 0.05), but did not affect lamb BW, ADG, or G:F (P ≥ 0.26). Despite that previous research shows differences in animal growth because of an increase in DDGS concentration, our experiments illustrated that heat processing or increased concentrations of DDGS up to 30% in finishing lamb diets are not responsible for a decrease in lamb performance.